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Shvoong Home>Science>Massive Black Holes enter the record book Summary

Massive Black Holes enter the record book

Article Summary   by:TanyaBiswasGanola     Original Author: Tanya Biswas Ganola
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Massive Black Hole enters the record Books

Astronomers have found the biggest stellar black hole so far, a monster with a mass of 15.65 times that of our Sun, lurking in a nearby spiral-shaped galaxy.
The find, located in a galaxy called Messier 33, has an even bigger companion – a close-orbitting star that is 70 times the mass of the sun, according to an investigation lead by Jerome Orosz of San Diago University, California. Black Holes are among the most powerful forces in the Universe. They are believed to be concentrated fields of gravity which are so powerful that nothing, not even light, can escape them.
Stellar black holes derive from the collapse of stars, but typically range from about three to 14 or 15solar masses.
Another category of black holes are “supermassive” holes spotted at the centre of galaxies, that have masses millions, and billions of, times that of the sun.
The Orosz team were able to make their calculations with the unusual accuracy, the estimate is plus or minus 1.45 solar masses- because the Messier 33 phenomenon is a so- called “eclipsing binary” .
This means that the companion star passes directly in front of the black hole in its 3.45 day orbit, blocking out X-ray emissions from the hole.
The regular fall and then rise in the X-ray signal provides the key indicator for calculating the “weight” of the hole.
Black holes can have any mass. Since gravity increases in inverse proportion to volume, any quantity of matter that is sufficiently compressed will become a black hole. However when a black hole forms naturally only a few mass ranges are realistic.
Published: October 21, 2007   
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